These results indicated that up-regulation of IFN-γ production might be important in the effect of PG on host defense to L. monocytogenes infection, Moreover, the IL-12p70 response was not enhanced by PG treatment before infection, but the response was markedly augmented in the spleen cells derived from PG-treated mice after infection (Fig. 5) as well as HKLM-stimulated mDC (Fig. 2), suggesting that PG treatment may play a role in Th1 differentiation in L. monocytogenes infection. This evidence concerns the gene IFNG and infection.